Centrifugal casting apparatus and method

Abstract

A centrifugal casting apparatus includes a rotatable assembly to rotate about a rotation axis. The rotatable assembly includes a sprue chamber positioned about the rotation axis and is shaped to receive a supply of molten material. A first gate and a second gate are positioned to receive molten material from the sprue chamber in a general direction of centrifugal force. A first cavity and a second cavity are stacked and are respectively positioned to receive molten material from the first gate and the second gate in the general direction of centrifugal force.

Description

BACKGROUND OF THE TECHNOLOGY[0001]1. Field of the Technology[0002]The present disclosure generally relates to equipment and techniques for centrifugal casting. The present disclosure more specifically relates to equipment and techniques for centrifugal casting of metallic materials.[0003]2. Description of the Background of the Technology[0004]Metallic casting generally includes supplying a volume of molten metallic material to a static or rotating mold and allowing the material to cool to produce a casting shaped by the mold. Castings may be cast in near net form or may be further modified in subsequent forging or machining applications to produce final components. Metallic materials shrink during phase transition from liquid to solid, which may result in castings comprising uncontrolled shrinkage porosity, especially in difficult to cast metallic materials such as, for example, titanium aluminide (TiAl) based alloys and other TiAl materials. Shrinkage porosity is inherent to the fu...

AI Technical Summary

Problems solved by technology

Metallic materials shrink during phase transition from liquid to solid, which may result in castings comprising uncontrolled shrinkage porosity, especially in difficult to cast metallic materials such as, for example, titanium aluminide (TiAl) based alloys and other TiAl materials.

Shrinkage porosity is inherent to the fundamental solidification mechanics and may negatively impact microstructure as well as casting yield.

However, uncontrolled internal porosity may result in surface distortions affecting surface quality of the casting and increase production costs.

Uncontrolled internal porosity may also be exposed when castings are sectioned or separated from casting components.

When porosity is surface connected, current processing techniques may be unsuitable for many casting applications.

For example, surface treatment techniques designed to fill or enclose porosity may fail to maintain the continuity of the casting, which may detrimentally affect mechanical properties of the cast material.

Material removal techniques such as machining to remove external porosity may also reduce casting yield and expose additional porosity.

Conventional casting techniques for casting various metallic materials, such as titanium aluminide based alloys, are incapable of controlling porosity such that the porosity is internalized away from both the surface of a casting and regions of the casting that may be subsequently sectioned.

These static casting techniques, however, create significant porosity, which cannot be removed using HIP.

Cooling rate and solidification, however, are difficult to control, as is evident by the requirement of a separate heating method and mold for each cast piece.

Although various other centrifugal casting techniques have been reported, none are able to adequately control shrinkage porosity.

Images